Control system



Aug. 23, 1938. P. THOMAS CONTROL SYSTEM Filed Aug. 14, 1929 ,7

Fig.1.

INVENTOR ATTORNEY Patented Aug. 23, 1938 UNITED STATES PATENT OFFICE inghouse Electric &

Manufacturing Company,

a corporation of Pennsylvania Application August 14,1929, Serial No. 385,915

8 Claims.

My invention relates to control systems and has particular relation to trafllc-control Systems.

The so-called program traflic-control systems known to the art include a controller and a motor for driving the same, electrically arranged to energize. sets of signal lights or stop and go traffic indications on two or more intersecting highways to permit the traflic on alternate highways to proceed.

As the terms stop indications and go indications are used hereinafter, they are assumed to mean any type of manifestation that indicates to traffic how it shall proceed. While such indication is ordinarily a visual manifestation such as a forms and traffic may in certain systems be restrained or be permitted to pass by the absence of any signal at all. The absence of a signal in such a case is of course also'an indication as the word is used here.

These systems are satisfactory when there is a uniform volume of trafiic of about equal proportions on each highway throughout the 24 hours of the day, but this condition seldom occurs in practice, so that, oftentimes, it is necessary for a vehicle on one highway to come to a stop and Wait during the change of signals, although no vehicles are present on the intersecting highway, thus resulting in loss of time and additional traffic congestion.

My invention is intended'to obviate these and other difficulties and, therefore, it is an object of my invention to provide a control system which will permit traflic to flow uninterruptedly along one of a number of intersecting highways but which will function on the approach of a vehicle on one of the intersecting highways to cause the traflic signal to go through a given sequence of signals.

Another object of my invention is to provide a device so arranged that, on failure of the actuating circuits, the control is transferred to a program control system.

Another object of my invention is to provide means whereby vehicles on a main highway may cause the traffic signal to be energized in a given sequence of signals to permit the vehicle to make a left-hand turn across the highway.

Other objects of my invention will become apparent in the following description of my invention taken in conjunction with the drawing.

Referring to the drawing, in which like figures indicate like parts,

Figure 1 is a schematic diagram of my trafliccontrol system, as applied to the intersection of signal light of a particular color, it may take other two highways, with the highways and traffic-con trol-system devices shown generally only, and

Fig. 2 is a view, partly in elevation and partly in section, of one of the highways showing portions of the traffic-control system installed there- In practicing my invention, I provide light-sensitive cells mounted in or adjacent to the traffic lanes and to the left-hand-turn lane in such manner that, on approach of a vehicle on any of the lanes, the traffic signal is caused to go through a'given sequence of stop, caution and go signals to permit vehicles on the left-hand-turn lanes or on the auxiliary lanes to enter into or cross the main highway.

Referring more particularly to Fig. 2 of the drawing, a light-sensitive cell C is disposed within a recess in a highway in such manner that day'- light or an artificial light source, such as the lamp I, suspended above thehighway, maintains the light-sensitive device in an energized condition, but, on the approach of a vehicle V, the light falling on the cell from the light source is interrupted and the light-sensitive cell is deenergized, causing a cooperating electromagnetic relay to drop to its deenergized position, thereby closing an electrical circuit hereinafter described, to actuate the traffic signals.

If'desired, a light-sensitive device CZ may be utilized for deenergizing the light source I during the day time and sun-light may be utilized for operating the light-sensitive cell. The light-sensitive cell C may be disposed in a recess in the highway, as shown, or may be disposed on astandard 2 at the side of the highway, with a light source mounted on the other side of the traffic lane, or the light-sensitive device may be disposed above the highway, with the light source mounted below the highway.

Referring more particularly to Fig. l, which shows the intersection of a major or main highway M and a minor or auxiliary highway A, the light-sensitive cells ON and CS are disposed in the traffic lanes to the right of the center of the auxiliary highway adjacent to the intersection, so that a vehicle approaching the intersection passes in close proximity to the light-sensitive device. The passage of the vehicle interrupts the light beam impinging upon one of the cells and causes one of the coacting relays RN and RS to become deenergized to break an electrical circuit hereinafter described.

Other light-sensitive cells, such as the cell CL, may be disposed in a left-hand-turn lane of the main highway, and relays, such as the relay BL, 55

associated therewith, may be utilized to control the signal to permit a vehicle to make a left-handturn across the main highway.

Electrical energy for energizing the traflic-control system is furnished by means of main-line conductors LI and L2. The relay control devices, which, in the present instance, comprise a lightsensitive cell C and a grid glow tube T, are disposed in series electrical relation with respect to their respective relays and in parallel electrical relation with each other.

Any suitable light-sensitive device may be utilized, but the light-sensitive device C here shown comprises a tube having an anode 3 and a cathode 4. When light impinges upon the cell, a discharge takes place between the anode and the cathode. The control electrode of the gridglow tube T is connected in parallel electrical relation to the cathode 4 of the light-sensitive cell C and, so long as the potential of the control electrode 5 is approximately the same as that of the anode of the grid-glow tube, a discharge takes place between the anode and the cathode of the grid-glow tube. Control of the Voltage at the terminals of the light-sensitive cell and the gridglow'tube and tuning of the circuit is effected by means of a rheostat 6 and a capacitance 1.

Any 'traffic signal known to the art may be utilized by a suitable modification of the electrical connections, but the traffic control signal, here shown, comprises three signal boxes dispose-d one above another. One signal lamp MG is adapted to display a green or go signal on the main highway and a red or stop signal on the side highway, when energized. Another signal Y is disposed to display a yellow or caution signal on both highways, and the third signal MR is arranged to show a red or stop signal on the main highway and a green or go signal on the side highway.

The signals may be caused to be actuated in sequence by means of a program controller PC driven by a program-controller motor POM. The signal controller ll of the program controller includes four. sectors adapted to control and ene'r'gize the three signal lights, as hereinafter described. A second controller disc 8, provided with a single insulated sector 21 of conducting material, is arranged to control and energize a program-control relay PCR, as hereinafter described.

The contacts of the relays RS, RL and RN are arranged in series electrical relation to each other and to the brushes 25 and 26 of the programcontrol sector RC and the coil of the programcontrol relay PCR. If a vehicle passes over any one'or more of the light-sensitive devices, the resistance between the anode and the cathode of the light-sensitive cell builds up until a discharge no longer takes place, and the difference of potential existing between the anode and. the cathode of the light-sensitive cell causes a difference of potential to exist between the control electrode 5 and the anode of the grid-glow tube T,'thereby causing a discharge between the anode and the cathode of the grid-glow tube to cease at the first zero-potential point in the alternating-current cycle. For example, suppose that a vehicle passes over the lightsensitive cell CS, the deenergization of the cell and the tube breaks the circuit which includes the corresponding relay RS, thus deenergizing the relay and permitting the contacts to open. Normally, the relay PCR, which, on closing, energizes the programcontrol motor, is held in its energized or open position by reason of the electrical circuit, which may be termed the relay circuit, including mainline conductor L2, conductor 2|, the contacts of relay RS, conductor 22, the contacts of relay RL, conductor 23, the contacts of relay RN, conductor 24, brush 25, sector 21, brush 26, conductor 28, the coil of the relay PCR, conductor 29 and mainline conductor LI.

When the sector 21 of the relay controller 8 is under the brushes 25 and 26 in its normal position, the brush 9 of the signal control makes electrical contact with sector 3|, and an electrical circuit is provided for energizing the main green signal MG, which includes main-line conductor Ll, conductor 30, the brush 9 of the signal controller, sector 3|, conductor 32, the lamp of the main green signal MG, conductor 33 and main-line conductor L2.

The breaking of the relay circuit by the dropping out of any one of the relays RS, RL or RN, because-of the passage of a vehicle, deenergizes the coil of the program-control relay PCR and causes a circuit to be established including the main-line conductor LI, conductor 34, the contacts of the program-control relay PCR, conductor 35, the program-controller motor PCM, conductor 35 and main-line conductor L2, thus causing the program-control motor to become energized, and the controller disc 8 and brush 9 of the signal controller H to rotate to effect a cycle of sequential operation of the stop, caution and go signals as hereinafter described.

After the brush 9 has rotated until it has lost contact with the sector controlling the signal MG, thus deenergizing it, contact is established with sector 3"]! and the yellow signal Y is energized by means of the circuit including conductors LI and 39, brush 9, sector 31, conductor 38, signal Y and conductor 33.

On further rotation of the brush, the circuit through the signal Y is broken, and a circuit is established through main-line conductor Ll conductor 35, brush 9, sector 39, conductor 4|, signal MR, conductor'33 and main-line conductor L2, to energize the MR signal to indicate red or stop on the main highway and green or go on the auxiliary highway. The vehicle standing in the auxiliary trafiic lanes or on the lefthand-turn lane may now cross or enter into the main'highway. The brush of the signal control PC continues to rotate and deenergizes the circuit including the signal MR and again energizes the signal Y. On further rotation, the brush deenergizes the signal Y and energizes the signal MG. Meanwhile, if no other vehicles have approached on the auxiliary highway or are in the left-hand-turn lane, the relays RS, 'RL, RN are all in their closed or energized position and, when sector 27 makes contact with brushes 25 and 26, the relay control circuit is reestablished through the program-control relay PCR, causing the coil to be energized and the contacts to become disengaged to stop the program-control motor.

The relay BL is preferably provided with a device known to the art which causes the relay to open after a certain predetermined length of time but is provided with an automatic reset feature which causes the relay to return fully to its energized position if only a portion of the time has elapsed. In this way, successive vehicles passing over the relay may not add their times to cause the relay eventually to function, but, if a single vehicle stops over the relay the required length of time, its contacts become disengaged to actuate the change of signals.

As used herein the terms lane, highway, thereby to prevent activation of said varying and thoroughfare are defined as follows:

A lane is a single traffic path along which traffic flows in one direction only.

A highway embraces a plurality of traflic paths along at least one of which traffic flows in a direction opposite to the direction of traific fiow along the others.

Thoroughfare is generic to both lane and highway and means either one or the other. A thoroughfare may also embrace two or more lanes in which trafiic fiows in the same direction.

Although I have described a specific embodiment of my invention, it is apparent that changes may be made therein without departing from the spirit and scope of my invention, asset forth in the appended claims. 1

I claim as my invention:

1. A traflic control system for two substantially parallel and opposite trafiic lanes, comprising a stop signal for each lane, means so disposed as to be actuated only by a unit of traffic in one lane taking a position to make a turn across the other lane and not by through trafiic in said one lane and means, to be actuated by said traffic-actuable means when. said trafficactuable means is actuated, for actuating a stop signal for said other lane.

2. A traflic control system for a plurality of intersecting highways comprising stop and go indications to be displayed for said highways, stop indications to be normally displayed for one of said highways and go indications to be normally displayed for another of said highways, means for so varying the display of said indications that go indications are displayed for said first-named highway and stop indications are displayed for said last-named highway and means, to be actuated by vehicles moving along said last-named highway and desiring to make a left-turn on the display of a stop indication for said last-named highway, for activating said varying means to vary the display of said indications, said means including timing means to cooperate with said varying means to prevent the activation of said varying means by said vehicle-responsive means unless said vehicleresponsive means has been actuated continuously for a predetermined interval of time which is appreciably longer than the interval during which said vehicle-responsive means is activated by a vehicle moving along said last named highway at a normal rate, thereby to prevent activation of said varying means by the actuation of said vehicle-responsive means by said last-named vehicles.

3. A traffic control system for the intersection of a thoroughfare and a highway comprising stop and go indications to be displayed for said highway, go indications displayed for said highway, means for so varying the display of said indications that stop indications are displayed for said highway and means, to be actuated by vehicles moving along said highway and desiring to make a left turn into said thoroughfare on the display of a stop indication for said highway, for activating said varying means to vary the display of said indications as aforesaid, said means including timing means to cooperate with said varying means to prevent the activation of said varying means unless said vehicle-responsive means has been actuated continuously for a predetermined interval of time which is appreciably longer than the interval during which said vehicle-responsive means is activated by vehicles moving along said highway at a normal rate,

means by the actuation of said vehicle-responsive means by said last-named vehicles.

4. A trafiic control system for a plurality of lanes including a first lane and a second lane comprising stop and go indications to be displayed for said first lane, go indications to be at times displayed for said first lane, means, when activated, for sojvarying the display of said indications that stop indications are displayed for said first lane and means, to be vehicle actuated, by vehicles moving along said second lane for activating said varying means, said vehicle-actuated means including timing means to permit the activation of said varying means only after said vehicle-actuated means is continuously actuated for a predetermined interval of time that is appreciably longer than the interval during which a vehicle moving along said second lane at a normal rate actuates said vehicle-responsive means thereby to prevent the variation of said indications by the coaction of said vehicle-responsive means and the last-named vehicles, said varying means being so activated, even if said vehicleactuated means is being actuated by a vehicle, that it is capable of effecting the display of a stop indication for said first lane while said vehicleactuated means continues to be actuated by said vehicle.

5. Traffic control apparatus for interfering trafiic lanes including signalling means for said lanes to interrupt right of way to traffic moving in one of said lanes, means to be actuated by vehicles in another of said lanes, and means responsive to actuation of said vehicle-actuable means for causing said signalling means to interrupt right of Way to traflic in the first said lane, the last said means including selecting means by the operation of which said responsive means operates said signalling means only when said vehicle-actuable means is actuated by a vehicle continuously for at least a predetermined interval of time Which is greater than the interval of time during which it would be actuated by a vehicle moving at a normal rate of speed along said lane and even if said vehicle actuable means continues to be actuated by said vehicle.

6. A traffic control system for two substantially parallel and opposite traffic lanes, comprising a stop signal for one of said lanes, means disposed as to be actuated only by a unit of traffic in the other of said lanes taking a position to make a turn across the said first-named lane and not by through traffic in said other lane and means, to be actuated by said traffic-actuable means when said traffic-actuable means is actu ated, for actuating said stop signal for said firstnamed lane;

7. A traffic control system for the intersection of a thoroughfare and a highway comprising stop and go indications to be displayed for one lane of said highway and for said thoroughfare, stop indications to be normally displayed for said thoroughfare and go indications to be normally displayed for said lane, means for so varying the display of said indications that go indications are displayed for said thoroughfare and stop indications are displayed for said lane, and means, to be actuated by vehicles moving along said highway in another lane and desiring to make a left turn across said first-named lane on the display of a stop indication for said lane, for actuating said varying means to vary the display of said indications as aforesaid, said Vehicle actuable means including timing means to cooperate with said varying means to prevent the actuation of said varying means by said vehicle-responsive means unless said vehicle-responsive means has been actuated continuously for a predetermined interval of time which is appreciably longer than the interval during which said vehicle-responsive means is actuated by a vehicle moving along said highway at a normal rate, thereby to prevent actuation of said varying means by the actuation of said vehicle-respomive means by said lastnamed vehicles.

8. A trafiic control system for the intersection of a thoroughfare and a highway comp-rising stop and go indications to be displayed for one lane of said highway, go indications to be normally displayed for said lane, means for so varying the display of said indications that stop indications are displayed for said lane, and means, to be actuated by vehicles moving along said highway in another'lane and desiring to make a left turn across said first-named lane on the display of a stop indication for said lane, for actuating said varying means to vary the display of said indications as aforesaid, said vehicle actuable means including timing means to cooperate with said varying means to prevent the actuation of said varying means by said vehicle-responsive means unless said vehicle-responsive means has been actuated continuously for a predetermined interval of time which is appreciably longer than the interval during which said vehicle-responsive means is actuated by a vehicle moving along said highway at a normal rate, thereby to prevent actuation of said varying means by the actuation ofsaid vehicle-responsive means by said lastnamed vehicles.

PHILLIPS THOMAS. 

